Often in cases of failing hearts, it's actually one side of the heart that doesn't work properly. A ventricular assistive device (VAD) is sometimes implanted, to help pump blood through the ventricle (chamber) on that side of the heart. There can be problems with conventional VADs, however, which a newly-developed soft robotic device may be able to address.
First of all, when a VAD pumps blood into a ventricle – the left ventricle, for example – it exerts pressure on the septum, which is the wall of tissue separating the left ventricle from the right. As a result, the septum can be pushed over into the healthy right ventricle, causing that ventricle to balloon and thus fail.
Secondly, because the blood passes through the unnatural environment of the VAD as it's pumped, the patient must take considerable amounts of anticoagulants in order to keep the blood from clotting. It can prove difficult to get the dosage just right, particularly with children.
That's where the soft robotic device comes in.
Developed by scientists from Boston Children's Hospital and Harvard University, it builds on technology announced earlier this year. The device cradles the compromised side of the heart, and incorporates soft actuators which expand to compress the ventricle, helping it to push blood out. Those actuators then relax and are drawn back by elastics, allowing the ventricle to fully open and draw in more blood.
Although the main unit sits outside the heart, a thin rigid brace extends from the device's outer frame and goes through the defective ventricle and into the septum where it's anchored (see the illustration above). This holds the septum in place, keeping it from being displaced.
Additionally, because the system doesn't require the blood to pass through a pump (as is the case with VADs), much less in the way of anticoagulants should be required.
The device has already been successfully tested on pigs. Lead scientist Dr. Nikolay Vasilyev and his team are now working at miniaturizing the technology and making it more portable, with an eye towards eventual use in humans.
A paper on the research was published this week in the journal Science Robotics.
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